57. Metallographie Tagung 2023

Correlative characterization of white etching layers in pearlitic rails.

Oleksandr Glushko1, Christoph Kammerhofer2, Juraj Todt1, Anna Jelinek1, Josef Keckes1, Ronald Schnitzer1
1 Department Materials Science, Montanuniversität Leoben, Franz-Josef str. 18, 8700 Leoben
2 voestalpine Rail Technology GmbH, Kerpelystraße 199, 8700 Leoben, Austria

A white etching layer (WEL) in pearlitic rail was induced by rolling contact fatigue experiments simulating different conditions appearing during rail operation. Distinct WELs and transition zone between WEL and base materials were observed using standard metallographic sample preparation and Nital etching. The employed correlative characterization approach includes the following techniques applied to the same area covering the WEL, transition layer and pristine microstructure:
- Optical microscopy after Nital etching
- Nanoindentation hardness and modulus mapping
- Detailed SEM and EBSD characterization
- Synchrotron XRD line scan
- Atom probe tomography (only WEL)
- Scanning transmission electron microscopy (only WEL)
Collected data enabled detailed description of spatial evolution of the grain size and phase distribution, when approaching WEL, with a direct link to the trend of nanoindentation hardness. Additional correlations with synchrotron diffraction data and high-resolution characterization allowed to establish a model describing the complex action of temperature and severe plastic deformation on the microstructure and phase evolution in the near-surface region of a rail.